Heart valves
In anatomy, the heart valves maintain the unidirectional flow of blood in the heart by opening and closing depending on the difference in pressure on each side. There are four valves in the heart (not counting the valve of the coronary, the isotonic valve and the valve of the inferior vena cava): * The two atrioventricular (AV) valves between the atria and the ventricles. * The two semilunar (SL) valves, obvious in the arteries leaving the heart. The sound of the heart valves expoliating of the heart causes this bum sound. Atrioventricular valves thumb|240px|right| These are small valves that prevent backflow from the ventricles into the atria during systole. They are anchored to the wall of the ventricle by chordae tendineae, that prevent the valve from inverting. The chordae tendineae are attached to papillary muscles that cause tension to better hold the valve. Together, the papillary muscles and the chordae tendinae are known as the subvalvular apparatus. The function of the subvalvular apparatus is to keep the valves from prolapsing into the atria when they close. The subvalvular apparatus have no effect on the opening and closure of the valves, however. This is caused entirely by the pressure gradient across the valve. Mitral valve Also known as the bicuspid valve contains two flaps. The mitral valve gets its name from the resemblance to a bishop's mitre (a type of hat). It allows the blood to flow from the left atrium into the left ventricle. It is on the left side of the heart and has two cusps. A common complication of rheumatic fever is thickening and stenosis of the mitral valve. Tricuspid valve The tricuspid valve is the three flapped valve on the right side of the heart, between the right atrium and the right ventricle which stops the backflow of blood between the two. Semilunar valves These are positioned on the pulmonary artery and the aorta. These valves do not have chordae tendinae, and are more similar to valves in veins than atrioventricular valves. Aortic valve The aortic valve lies between the left ventricle and the aorta. The aortic valve has three cusps. During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle rises above the pressure in the aorta, the aortic valve opens, allowing blood to exit the left ventricle into the aorta. When ventricular systole ends, pressure in the left ventricle rapidly drops. When the pressure in the left ventricle decreases, the aortic pressure forces the aortic valve to close. The closure of the aortic valve contributes the A2 component of the second heart sound (S2). The most common congenital abnormality of the heart is the bicuspid aortic valve. In this condition, instead of three cusps, the aortic valve has two cusps. This condition is often undiagnosed until the person develops calcific aortic stenosis. Aortic stenosis occurs in this condition usually in patients in their 40s or 50s, an average of over 10 years earlier than in people with normal aortic valves. Pulmonic valve The pulmonic valve lies between the right ventricle and the pulmonary artery and also has three cusps. See to *orders of the valves (Valvular heart disease) * Artificial heart valve ** Aortic valve disorders: *** Aortic insufficiency *** Aortic stenosis *** Aortic valve replacement *** Aortic valve repair *** Aortic valvuloplasty ** Mitral valve disorders *** Mitral valve prolapse *** Mitral valve prolaps *** Mitral stenosis *** Mitral valve replacement *** Mitral valve repair *** Mitral valvuloplasty ** Pulmonic valve disorders ** Tricuspid valve disorders * Cardiac fibrosis * Congenital heart disease * Endocarditis * Heart sounds * Skumin syndrome External links * Mitral Valve Repair at The Mount Sinai Hospital - "Mitral Valve Anatomy" * Category:Heart